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  <div class="section" id="generateexportheader">
<span id="module:GenerateExportHeader"></span><h1>GenerateExportHeader<a class="headerlink" href="#generateexportheader" title="Permalink to this headline">¶</a></h1>
<p>Function for generation of export macros for libraries</p>
<p>This module provides the function <code class="docutils literal notranslate"><span class="pre">GENERATE_EXPORT_HEADER()</span></code>.</p>
<p>The <code class="docutils literal notranslate"><span class="pre">GENERATE_EXPORT_HEADER</span></code> function can be used to generate a file
suitable for preprocessor inclusion which contains EXPORT macros to be
used in library classes:</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>GENERATE_EXPORT_HEADER( LIBRARY_TARGET
          [BASE_NAME &lt;base_name&gt;]
          [EXPORT_MACRO_NAME &lt;export_macro_name&gt;]
          [EXPORT_FILE_NAME &lt;export_file_name&gt;]
          [DEPRECATED_MACRO_NAME &lt;deprecated_macro_name&gt;]
          [NO_EXPORT_MACRO_NAME &lt;no_export_macro_name&gt;]
          [INCLUDE_GUARD_NAME &lt;include_guard_name&gt;]
          [STATIC_DEFINE &lt;static_define&gt;]
          [NO_DEPRECATED_MACRO_NAME &lt;no_deprecated_macro_name&gt;]
          [DEFINE_NO_DEPRECATED]
          [PREFIX_NAME &lt;prefix_name&gt;]
          [CUSTOM_CONTENT_FROM_VARIABLE &lt;variable&gt;]
)
</pre></div>
</div>
<p>The target properties <span class="target" id="index-0-prop_tgt:&lt;LANG&gt;_VISIBILITY_PRESET"></span><a class="reference internal" href="../prop_tgt/LANG_VISIBILITY_PRESET.html#prop_tgt:&lt;LANG&gt;_VISIBILITY_PRESET" title="&lt;LANG&gt;_VISIBILITY_PRESET"><code class="xref cmake cmake-prop_tgt docutils literal notranslate"><span class="pre">CXX_VISIBILITY_PRESET</span></code></a>
and <span class="target" id="index-0-prop_tgt:VISIBILITY_INLINES_HIDDEN"></span><a class="reference internal" href="../prop_tgt/VISIBILITY_INLINES_HIDDEN.html#prop_tgt:VISIBILITY_INLINES_HIDDEN" title="VISIBILITY_INLINES_HIDDEN"><code class="xref cmake cmake-prop_tgt docutils literal notranslate"><span class="pre">VISIBILITY_INLINES_HIDDEN</span></code></a> can be used to add the appropriate
compile flags for targets.  See the documentation of those target properties,
and the convenience variables
<span class="target" id="index-0-variable:CMAKE_&lt;LANG&gt;_VISIBILITY_PRESET"></span><a class="reference internal" href="../variable/CMAKE_LANG_VISIBILITY_PRESET.html#variable:CMAKE_&lt;LANG&gt;_VISIBILITY_PRESET" title="CMAKE_&lt;LANG&gt;_VISIBILITY_PRESET"><code class="xref cmake cmake-variable docutils literal notranslate"><span class="pre">CMAKE_CXX_VISIBILITY_PRESET</span></code></a> and
<span class="target" id="index-0-variable:CMAKE_VISIBILITY_INLINES_HIDDEN"></span><a class="reference internal" href="../variable/CMAKE_VISIBILITY_INLINES_HIDDEN.html#variable:CMAKE_VISIBILITY_INLINES_HIDDEN" title="CMAKE_VISIBILITY_INLINES_HIDDEN"><code class="xref cmake cmake-variable docutils literal notranslate"><span class="pre">CMAKE_VISIBILITY_INLINES_HIDDEN</span></code></a>.</p>
<p>By default <code class="docutils literal notranslate"><span class="pre">GENERATE_EXPORT_HEADER()</span></code> generates macro names in a file
name determined by the name of the library.  This means that in the
simplest case, users of <code class="docutils literal notranslate"><span class="pre">GenerateExportHeader</span></code> will be equivalent to:</p>
<div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">set(</span><span class="no">CMAKE_CXX_VISIBILITY_PRESET</span><span class="w"> </span><span class="nb">hidden</span><span class="nf">)</span><span class="w"></span>
<span class="nf">set(</span><span class="no">CMAKE_VISIBILITY_INLINES_HIDDEN</span><span class="w"> </span><span class="m">1</span><span class="nf">)</span><span class="w"></span>
<span class="nf">add_library(</span><span class="nb">somelib</span><span class="w"> </span><span class="nb">someclass.cpp</span><span class="nf">)</span><span class="w"></span>
<span class="nf">generate_export_header(</span><span class="nb">somelib</span><span class="nf">)</span><span class="w"></span>
<span class="nf">install(</span><span class="no">TARGETS</span><span class="w"> </span><span class="nb">somelib</span><span class="w"> </span><span class="no">DESTINATION</span><span class="w"> </span><span class="o">${</span><span class="nt">LIBRARY_INSTALL_DIR</span><span class="o">}</span><span class="nf">)</span><span class="w"></span>
<span class="nf">install(</span><span class="no">FILES</span><span class="w"></span>
<span class="w"> </span><span class="nb">someclass.h</span><span class="w"></span>
<span class="w"> </span><span class="o">${</span><span class="nt">PROJECT_BINARY_DIR</span><span class="o">}</span><span class="na">/somelib_export.h</span><span class="w"> </span><span class="no">DESTINATION</span><span class="w"> </span><span class="o">${</span><span class="nt">INCLUDE_INSTALL_DIR</span><span class="o">}</span><span class="w"></span>
<span class="nf">)</span><span class="w"></span>
</pre></div>
</div>
<p>And in the ABI header files:</p>
<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="cp">#include</span> <span class="cpf">&quot;somelib_export.h&quot;</span><span class="cp"></span>
<span class="k">class</span> <span class="nc">SOMELIB_EXPORT</span> <span class="n">SomeClass</span> <span class="p">{</span>
  <span class="p">...</span>
<span class="p">};</span>
</pre></div>
</div>
<p>The CMake fragment will generate a file in the
<code class="docutils literal notranslate"><span class="pre">${CMAKE_CURRENT_BINARY_DIR}</span></code> called <code class="docutils literal notranslate"><span class="pre">somelib_export.h</span></code> containing the
macros <code class="docutils literal notranslate"><span class="pre">SOMELIB_EXPORT</span></code>, <code class="docutils literal notranslate"><span class="pre">SOMELIB_NO_EXPORT</span></code>, <code class="docutils literal notranslate"><span class="pre">SOMELIB_DEPRECATED</span></code>,
<code class="docutils literal notranslate"><span class="pre">SOMELIB_DEPRECATED_EXPORT</span></code> and <code class="docutils literal notranslate"><span class="pre">SOMELIB_DEPRECATED_NO_EXPORT</span></code>.
They will be followed by content taken from the variable specified by
the <code class="docutils literal notranslate"><span class="pre">CUSTOM_CONTENT_FROM_VARIABLE</span></code> option, if any.
The resulting file should be installed with other headers in the library.</p>
<p>The <code class="docutils literal notranslate"><span class="pre">BASE_NAME</span></code> argument can be used to override the file name and the
names used for the macros:</p>
<div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">add_library(</span><span class="nb">somelib</span><span class="w"> </span><span class="nb">someclass.cpp</span><span class="nf">)</span><span class="w"></span>
<span class="nf">generate_export_header(</span><span class="nb">somelib</span><span class="w"></span>
<span class="w">  </span><span class="no">BASE_NAME</span><span class="w"> </span><span class="nb">other_name</span><span class="w"></span>
<span class="nf">)</span><span class="w"></span>
</pre></div>
</div>
<p>Generates a file called <code class="docutils literal notranslate"><span class="pre">other_name_export.h</span></code> containing the macros
<code class="docutils literal notranslate"><span class="pre">OTHER_NAME_EXPORT</span></code>, <code class="docutils literal notranslate"><span class="pre">OTHER_NAME_NO_EXPORT</span></code> and <code class="docutils literal notranslate"><span class="pre">OTHER_NAME_DEPRECATED</span></code>
etc.</p>
<p>The <code class="docutils literal notranslate"><span class="pre">BASE_NAME</span></code> may be overridden by specifying other options in the
function.  For example:</p>
<div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">add_library(</span><span class="nb">somelib</span><span class="w"> </span><span class="nb">someclass.cpp</span><span class="nf">)</span><span class="w"></span>
<span class="nf">generate_export_header(</span><span class="nb">somelib</span><span class="w"></span>
<span class="w">  </span><span class="no">EXPORT_MACRO_NAME</span><span class="w"> </span><span class="no">OTHER_NAME_EXPORT</span><span class="w"></span>
<span class="nf">)</span><span class="w"></span>
</pre></div>
</div>
<p>creates the macro <code class="docutils literal notranslate"><span class="pre">OTHER_NAME_EXPORT</span></code> instead of <code class="docutils literal notranslate"><span class="pre">SOMELIB_EXPORT</span></code>, but
other macros and the generated file name is as default:</p>
<div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">add_library(</span><span class="nb">somelib</span><span class="w"> </span><span class="nb">someclass.cpp</span><span class="nf">)</span><span class="w"></span>
<span class="nf">generate_export_header(</span><span class="nb">somelib</span><span class="w"></span>
<span class="w">  </span><span class="no">DEPRECATED_MACRO_NAME</span><span class="w"> </span><span class="no">KDE_DEPRECATED</span><span class="w"></span>
<span class="nf">)</span><span class="w"></span>
</pre></div>
</div>
<p>creates the macro <code class="docutils literal notranslate"><span class="pre">KDE_DEPRECATED</span></code> instead of <code class="docutils literal notranslate"><span class="pre">SOMELIB_DEPRECATED</span></code>.</p>
<p>If <code class="docutils literal notranslate"><span class="pre">LIBRARY_TARGET</span></code> is a static library, macros are defined without
values.</p>
<p>If the same sources are used to create both a shared and a static
library, the uppercased symbol <code class="docutils literal notranslate"><span class="pre">${BASE_NAME}_STATIC_DEFINE</span></code> should be
used when building the static library:</p>
<div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">add_library(</span><span class="nb">shared_variant</span><span class="w"> </span><span class="no">SHARED</span><span class="w"> </span><span class="o">${</span><span class="nt">lib_SRCS</span><span class="o">}</span><span class="nf">)</span><span class="w"></span>
<span class="nf">add_library(</span><span class="nb">static_variant</span><span class="w"> </span><span class="o">${</span><span class="nt">lib_SRCS</span><span class="o">}</span><span class="nf">)</span><span class="w"></span>
<span class="nf">generate_export_header(</span><span class="nb">shared_variant</span><span class="w"> </span><span class="no">BASE_NAME</span><span class="w"> </span><span class="nb">libshared_and_static</span><span class="nf">)</span><span class="w"></span>
<span class="nf">set_target_properties(</span><span class="nb">static_variant</span><span class="w"> </span><span class="no">PROPERTIES</span><span class="w"></span>
<span class="w">  </span><span class="no">COMPILE_FLAGS</span><span class="w"> </span><span class="p">-</span><span class="no">DLIBSHARED_AND_STATIC_STATIC_DEFINE</span><span class="nf">)</span><span class="w"></span>
</pre></div>
</div>
<p>This will cause the export macros to expand to nothing when building
the static library.</p>
<p>If <code class="docutils literal notranslate"><span class="pre">DEFINE_NO_DEPRECATED</span></code> is specified, then a macro
<code class="docutils literal notranslate"><span class="pre">${BASE_NAME}_NO_DEPRECATED</span></code> will be defined This macro can be used to
remove deprecated code from preprocessor output:</p>
<div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">option(</span><span class="no">EXCLUDE_DEPRECATED</span><span class="w"> </span><span class="s">&quot;Exclude deprecated parts of the library&quot;</span><span class="w"> </span><span class="no">FALSE</span><span class="nf">)</span><span class="w"></span>
<span class="nf">if</span> <span class="nf">(</span><span class="no">EXCLUDE_DEPRECATED</span><span class="nf">)</span><span class="w"></span>
<span class="w">  </span><span class="nf">set(</span><span class="no">NO_BUILD_DEPRECATED</span><span class="w"> </span><span class="no">DEFINE_NO_DEPRECATED</span><span class="nf">)</span><span class="w"></span>
<span class="nf">endif()</span><span class="w"></span>
<span class="nf">generate_export_header(</span><span class="nb">somelib</span><span class="w"> </span><span class="o">${</span><span class="nt">NO_BUILD_DEPRECATED</span><span class="o">}</span><span class="nf">)</span><span class="w"></span>
</pre></div>
</div>
<p>And then in somelib:</p>
<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="k">class</span> <span class="nc">SOMELIB_EXPORT</span> <span class="n">SomeClass</span>
<span class="p">{</span>
<span class="k">public</span><span class="o">:</span>
<span class="cp">#ifndef SOMELIB_NO_DEPRECATED</span>
  <span class="n">SOMELIB_DEPRECATED</span> <span class="kt">void</span> <span class="n">oldMethod</span><span class="p">();</span>
<span class="cp">#endif</span>
<span class="p">};</span>
</pre></div>
</div>
<div class="highlight-c++ notranslate"><div class="highlight"><pre><span></span><span class="cp">#ifndef SOMELIB_NO_DEPRECATED</span>
<span class="kt">void</span> <span class="n">SomeClass</span><span class="o">::</span><span class="n">oldMethod</span><span class="p">()</span> <span class="p">{</span>  <span class="p">}</span>
<span class="cp">#endif</span>
</pre></div>
</div>
<p>If <code class="docutils literal notranslate"><span class="pre">PREFIX_NAME</span></code> is specified, the argument will be used as a prefix to
all generated macros.</p>
<p>For example:</p>
<div class="highlight-cmake notranslate"><div class="highlight"><pre><span></span><span class="nf">generate_export_header(</span><span class="nb">somelib</span><span class="w"> </span><span class="no">PREFIX_NAME</span><span class="w"> </span><span class="no">VTK_</span><span class="nf">)</span><span class="w"></span>
</pre></div>
</div>
<p>Generates the macros <code class="docutils literal notranslate"><span class="pre">VTK_SOMELIB_EXPORT</span></code> etc.</p>
<div class="highlight-none notranslate"><div class="highlight"><pre><span></span>ADD_COMPILER_EXPORT_FLAGS( [&lt;output_variable&gt;] )
</pre></div>
</div>
<p>The <code class="docutils literal notranslate"><span class="pre">ADD_COMPILER_EXPORT_FLAGS</span></code> function adds <code class="docutils literal notranslate"><span class="pre">-fvisibility=hidden</span></code> to
<span class="target" id="index-0-variable:CMAKE_&lt;LANG&gt;_FLAGS"></span><a class="reference internal" href="../variable/CMAKE_LANG_FLAGS.html#variable:CMAKE_&lt;LANG&gt;_FLAGS" title="CMAKE_&lt;LANG&gt;_FLAGS"><code class="xref cmake cmake-variable docutils literal notranslate"><span class="pre">CMAKE_CXX_FLAGS</span></code></a> if supported, and is a no-op
on Windows which does not need extra compiler flags for exporting support.
You may optionally pass a single argument to <code class="docutils literal notranslate"><span class="pre">ADD_COMPILER_EXPORT_FLAGS</span></code>
that will be populated with the <code class="docutils literal notranslate"><span class="pre">CXX_FLAGS</span></code> required to enable visibility
support for the compiler/architecture in use.</p>
<p>This function is deprecated.  Set the target properties
<span class="target" id="index-1-prop_tgt:&lt;LANG&gt;_VISIBILITY_PRESET"></span><a class="reference internal" href="../prop_tgt/LANG_VISIBILITY_PRESET.html#prop_tgt:&lt;LANG&gt;_VISIBILITY_PRESET" title="&lt;LANG&gt;_VISIBILITY_PRESET"><code class="xref cmake cmake-prop_tgt docutils literal notranslate"><span class="pre">CXX_VISIBILITY_PRESET</span></code></a> and
<span class="target" id="index-1-prop_tgt:VISIBILITY_INLINES_HIDDEN"></span><a class="reference internal" href="../prop_tgt/VISIBILITY_INLINES_HIDDEN.html#prop_tgt:VISIBILITY_INLINES_HIDDEN" title="VISIBILITY_INLINES_HIDDEN"><code class="xref cmake cmake-prop_tgt docutils literal notranslate"><span class="pre">VISIBILITY_INLINES_HIDDEN</span></code></a> instead.</p>
</div>


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